Open Timber Truss

Vermont's earliest bridges were simple, open timber
trusses, the technology for which was likely brought over by the first European
settlers. In 1785, Enoch Hale, a builder
from Rowley, Massachusetts, constructed one of the country's first timber frame
bridges across the Connecticut River between Walpole, New Hampshire, and
Bellows Falls, Vermont. From the
18th century through the early 20th century, timber frame
bridges populated Vermont's rural roads.
Many, however, have been replaced or were lost during the 1927
flood. Two truss types were
dominant in timber bridge construction: king post and queen post.

The king post truss, consisting of one vertical post
at the center of a triangle, was primarily suitable for spans less than 50
feet. Multiple king post trusses
allowed a longer span. A single
king post is seen in the image on the left, while a multiple king post is seen
on the right.

King Post Trusses: Image courtesy of Robert McCullough, Crossings: A
History of Vermont Bridges, 2005

King post trusses were sometimes left open, as seen in
the images above, but often, particularly in the northeastern states, the
bridge was clad in boards or shingles.

King Post Trusses Clad on Sheathing Boards: Image courtesy of Robert McCullough

The queen post truss, which consisted of two vertical
posts intersecting the sides of a triangle and connected at the top by a
horizontal beam, was suitable for slightly longer spans than the king
post. These too were often
sheathed in boards or shingles.